I deleted all the files in the c4doctane folder and copied the new files there, of course I kept only the "c4dOctane-r15.cdl64", like it was written, in the readme.txt. Additionally, I deinstalled the old standalone version and installed the new one.

Do I have to delete files in the c4d folder ...

I installed the new version of the C4D plugin , 1.53, and the new standalone version correctly, like it was shown in the readme.txt file.

But cinema 4D Release 15 crashes when I try to create a new octane material.

Please someone help me!